HD44454 is the first program of research to investigate educationally relevant environments and their influence on outcomes in a genetically sensitive design in order to understand their genetic as well as environmental origins. The proposed research will extend HD44454 from childhood (age 10) to adolescence (age 15). The research will test three related hypotheses: (1) Twins, even identical twins, in the same school experience different environments, (2) Children's educational experiences are significantly influenced by genetic factors, and (3) Associations between educational experiences and outcomes are significantly influenced by genetic factors as well as by environmental factors. The project will capitalize on the Twins Early Development Study (TEDS), a representative twin sample in childhood born in 1994-96 and assessed at 2, 3, 4, 7, 9, 10, and 12 years on measures of cognition, school achievement, and behavior problems. As part of HD44454, children's school and classroom environments as perceived by the children themselves were assessed when the children were age 9 and 10. The proposed extension of HD44454 will follow 8000 of these children into adolescence and assess them and their school environments again at age 15 once a week for a month using a diary/interview method developed and tested in HD44454. As well as providing a weekly diary account of their school experience, participants will be interviewed in detail about four important learning environments, one in each week of the study: home, school, subject-specific classrooms, and peers. Educational experiences at age 15 are critical as adolescents begin to make choices about education and careers beyond high school. Age 15 is also the leading edge of the peak age of risk for the development of adult psychiatric problems. The proposed extension of HD44454 to age 15 will investigate the role of educational experiences in academic, cognitive and adjustment outcomes in a genetically sensitive design. These new data on school environments at age 15 will also be analyzed in relation to the HD44454 data on these children at age 10 and to the rest of the rich longitudinal TEDS dataset from infancy, which now includes DNA genotyped on two million DNA markers for 4000 children.